#include <iostream>
using namespace std;
int main()
{
    int a;
    cout << "请输入多边形的边数:" ;
    cin >> a;
    int b;
    b = a - 2;
    int c;
    c = b * 180;
    cout << "此多边形的内角和是：" << c << "°" << endl;
    return 0;
}
